iOS Core Data错误 - 一对多关系的不可接受的值类型 [英] iOS Core Data error - Unacceptable type of value for to-many relationship

问题描述

我在这个问题上撕掉了我的头发，这似乎应该是很简单的东西。 iOS / Objective C对我来说是新的，所以也许我只是没有抓住基本的东西。

问题是我已经添加了一个新的实体到我的核心数据模型，并设置一对多的关系。模型已经有两个具有一对一关系的实体。

玩家实体是新的。

我有一个UITableViewController，我从UITextFields保存到属性。这对于Teams / TeamDetails的原始配置工作正常，但是当我将Players实体添加到代码时，会出现以下错误：

 由于未捕获异常而终止应用程序'NSInvalidArgumentException'，
原因：'多对多关系的不可接受的值类型：
 property =playerDetails;所需类型= NSSet;给定类型=玩家; 
  

所以，在我的保存方法中，我有：

  Teams * team = [NSEntityDescription insertNewObjectForEntityForName：@TeamsinManagedObjectContext：self.managedObjectContext]; 
 TeamDetails * teamdetails = [NSEntityDescription insertNewObjectForEntityForName：@TeamDetailsinManagedObjectContext：self.managedObjectContext]; 
 
 team.teamDetails = teamdetails; 
  

然后我继续设置属性：

  team.teamName = teamNameTextField.text; 
 team.teamDetails.managerName = managerNameTextField.text; 
  

这些都没有问题。现在我扩展到包含玩家实体：

 玩家* playerDetails = [NSEntityDescription insertNewObjectForEntityForName：@PlayersinManagedObjectContext：self。 managedObjectContext]; 
 
 team.playerDetails = playerDetails; 
  

我得到上面的错误。我试过以下：

  [team setPlayerDetails：playerDetails]; 
  

但这没有什么区别。我也尝试过：

  NSSet * playerDetails = [NSEntityDescription insertNewObjectForEntityForName：@PlayersinManagedObjectContext：self.managedObjectContext]; 
  

但是，没有什么区别 - 它仍然认为它是一个类型Players的对象，而不是NSSet。 / p>

我觉得我只是没有抓住一些简单的东西，所以任何帮助将非常赞赏！

解决方案

playerDetails 是一个多对多关系，因此 team.playerDetails 是一个设置的玩家，而不是单个玩家对象。您可以使用

  [team addPlayerDetailsObject：playerDetails]; 
  

或更简单，使用反比关系：

  playerDetails.team = team; 
  

I'm tearing my hair out with this issue, which seems like it should be something really simple. iOS / Objective C is new to me, so maybe I'm just not grasping something fundamental.

The problem is that I've added a new entity to my Core Data model, and set up a one-to-many relationship. The model already had two entities that had a one-to-one relationship.

The Players entity is the new one.

I have a UITableViewController where I'm saving to the attributes from UITextFields. This worked fine for the original configuration of Teams/TeamDetails, but it crashes out with the following error when I add in the Players entity to the code:

Terminating app due to uncaught exception 'NSInvalidArgumentException', 
reason:   'Unacceptable type of value for to-many relationship: 
property = "playerDetails"; desired type = NSSet; given type = Players;

So, in my Save method, I had:

Teams *team = [NSEntityDescription insertNewObjectForEntityForName:@"Teams" inManagedObjectContext:self.managedObjectContext];
TeamDetails *teamdetails = [NSEntityDescription insertNewObjectForEntityForName:@"TeamDetails" inManagedObjectContext:self.managedObjectContext];

team.teamDetails = teamdetails;

then I go on to set the attributes like:

team.teamName = teamNameTextField.text;
team.teamDetails.managerName = managerNameTextField.text;

Which all worked no problem. Now I extend this to incorporate the Players Entity:

Players *playerDetails = [NSEntityDescription insertNewObjectForEntityForName:@"Players" inManagedObjectContext:self.managedObjectContext];

team.playerDetails = playerDetails;

And I get the error above. I've tried the following:

[team setPlayerDetails:playerDetails];

But this doesn't make any difference. I also tried:

NSSet *playerDetails = [NSEntityDescription insertNewObjectForEntityForName:@"Players" inManagedObjectContext:self.managedObjectContext];

But again, no difference - it still thinks it's getting an object of type Players rather than NSSet.

I feel like I'm just not grasping something simple, so any help would ge very much appreciated!

解决方案

playerDetails is a to-many relationship, so the value of team.playerDetails is a set of players, not a single player object. You can either use

[team addPlayerDetailsObject:playerDetails];

or more simply, using the inverse relationship:

playerDetails.team = team;

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